LINQ queries

The recommended way to create queries is to use LINQ. If you are unfamiliar with LINQ, have a look at https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/linq/get-started-with-linq.

To fully use LINQ querying, make sure to have the following usings:

using System.Linq;
using Stylelabs.M.Base.Querying;
using Stylelabs.M.Base.Querying.Linq;

The LINQ template is as follows:

var query = Query.CreateQuery(entities => 
  from e in entities
  where [conditions]
  orderby [property] ascending | descending
  select e);

Multiple conditions in the where clause can be chained by using &&.

orderby can be used to order results based on certain (system) properties, either ascending or descending. Multiple orderby statements can be used for more complex ordering.

The following filters on entities are supported for LINQ querying.

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.Id == entityId
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.Property("Title") == "Logo"
  select e);

Depending on the system property data type:

For example, to filter entities modified after the specified date:

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.ModifiedOn > dateTime
  select e);

Depending on the property data type:

For example, to filter entities where the title is not "Logo":

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.Property("Title") != "Logo"
  select e);

The In filter allows specifying a collection or comma separated values that, it allows filtering on multiple values instead of a single one.

The In filter is supported on:

Let's find the entities where the title is set to "Logo" or "Poster":

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.Property("Title").In("Logo", "Poster")
  select e);

String properties support some additional filters:

These filters are not case sensitive.

The following query can be used to find all entities with a Title property that contains "logo".

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.Property("Title").Contains("logo")
  select e);

Ordering is supported on:

For example, to order assets on creation date, and then by title:

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.DefinitionName == "M.Asset"
  orderby e.CreatedOn ascending
  orderby e.Property("Title") ascending
  select e);

Currently only load and configuration operations are support on the select clause.

The following select options are supported:

Multiple of these select options can be chained. The last operation will always overwrite the previous one where applicable.

In this example, we start from the default query load configuration (loads default culture, all properties and no relations) and we add the AssetTypeToAsset relation. The WithRelations overwrites the relation load option on the load configuration set earlier.

var query = Query.CreateQuery(entities => 
  from e in entities
  where [conditions]
  select e.LoadConfiguration(QueryLoadConfiguration.Default)
  .WithRelations(new RelationLoadOption("AssetTypeToAsset")));

skip (skip the first x entities) and take (return x entities) are also supported when using LINQ:

var query = Query.CreateQuery(entities => 
  (from e in entities
  where [your conditions]
  select e)
  .Skip(5)
  .Take(5));

This orders the entities by ID descending, skips the first 5 entities (the 5 newest entities) and then returns the next 5 entities.

The following is a list of examples. Most of these examples are very simple and self explanatory. Examples tend to be more complex towards the end.

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.Id == entityId
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.Identifier == entityIdentifier
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.DefinitionId == definitionId
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.DefinitionName == "M.Asset"
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.CreatedById == demoUserId
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.CreatedByUsername == "M.Demo.User"
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.ModifiedById == demoUserId
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.ModifiedByUsername == "M.Demo.User"
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.CreatedOn == dateTime
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.CreatedOn  minDateTime && e.CreatedOn  maxDateTime
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.ModifiedOn == dateTime
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.ModifiedOn  minDateTime && e.ModifiedOn  maxDateTime
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.Property("Title") == "Logo"
  select e);

CultureInfo enUs = CultureInfo.GetCultureInfo("en-US");
var query = Query.CreateQuery(entities => 
  from e in entities
  where e.Property("Description", enUs) == "Hello world!"
  select e);

var query = Query.CreateQuery(entities => 
  from e in entities
  where e.Parent("AssetTypeToAsset") == assetTypeId
  select e);